SUCCESSIONS OF THE SAT TAL VALLEY. 251
Tal, and lakes with gently sloping shores such as a swampy lake just to the north-east of the valley.
Streams are occupied by such pioneers as Debregcasia hypoleuca of the Nettle Family and Colebroohia oppositifolia of the Mint Family, then the rosaceous shrubs, then trees of the Laurel Family with perhaps a few Rhododendrons which have temporarily gone a little below their normal range, then, in the altitude of Sat Tal valley, generally the oak climax.
Lakes with steeper shores have following the aquatics of deep water the willow, Salix daphnoides, near the water's edge. This adapts itself to the shifting seasonal water level by putting out roots at high water mark which hang high and dry when the water is low. As the lake decreases for topographical reasons, the willow is followed by rosaceous shrubs leading ultimately to the oak.
Lakes with gentle slopes, or swamps, have a large quota of sub- mersed and floating aquatics. These are succeeded by Typha angus- tata, Scirpus spp., and Polygonum lanigerum, which are followed, as the water becomes more shallow, by Acorns calamus and Panicum paspaloidcs. Later comes the wet meadow and then the Berbcris- Rosaccac formation leading to the oaks.
Special Features of the Vegetation.
About fifteen of the tree and shrub species in the valley are above the altitudinal range given for them by Brandis (2). Probably the fact that the valley is a depression protected from cold winds by the peak to the north, has allowed plants to grow out of their ordinary range.
A noteworthy feature of this altitude in the Himalayas is the abundance of lianas. Over twenty of the woody plants in the appended species list are climbers, to say nothing of many climbing herbs. A single tree was noticed which supported eight different species of climbers. Bauhinia vahlii is the king of lianas here. The Naini Tal Gazeteer (8) states that at times it grows so profusely that a single plant will cover a quarter of an acre of forest. It has been found a great pest to the forester as it overshadows and stunts the growth of many trees. So prolifically does it ooppice that the foresters have difficulty in suppressing it. The valley has three genera of climbing aroids, four species of Vitis, and numerous leguminous clim- bers, climbing figs., etc. One of the most widespread lianas is the common ivy. Partaking of the nature of both lianas and epiphytes, and embracing tree trunks with a network of roots often to the extent of considerable injury to the tree embraced are certain species of Ficus, as F Rumphii, (the so-called " strangling figs ") and Heptopleu- rum venulosum, a member of the Araliaceae.
